Drugs Physical Activity Surgery and other Treatment for Overweight and Obesity - Physical Activity

In sharp contrast to the Amish farmers, many Americans in the early twenty-first century are not physically active—in 2000 the percent of adults age eighteen or older that was inactive was higher for women (12 percent) than men (7 percent) and increased sharply with age. Nearly one-fifth of men over age sixty-five and one-quarter of women over age sixty-five were inactive. (See Figure 6.1.) Since most Americans engage in sedentary work, much of their physical activity occurs while performing routine household activities and during leisure time. Figure 6.2 shows that the annual proportion of adults age eighteen or over that engaged in regular leisure-time physical activity increased from 29.9 percent in 1998 to 31.9 percent in 2000, but has not significantly increased since 2000. Participation in leisure-time physical activity decreased with age among persons of both genders, and in every age group fewer women than men spent their leisure time in active physical pursuits. (See Figure 6.3.) National Health Interview Survey data from the first six months of 2003 also indicated that non-Hispanic white adults were more likely to engage in leisure-time physical activity (35.9 percent) than Hispanic adults (24.7 percent) and non-Hispanic black adults (26.5 percent). (See Figure 6.4.)

Physical Activity and Weight Loss

Increasing physical activity and exercise is an important element of regimens intended to produce weight loss, even though the addition of exercise to a diet program generally does not produce substantially greater weight FIGURE 6.1
Adults who are inactive or have a low level of overall physical activity, by age and sex, 2000 loss—the majority of weight lost is attributable to decreased caloric intake. By favorably affecting blood lipids, increased and sustained physical activity does offer many direct and indirect health benefits including reducing risks for cardiovascular heart disease and Type 2 diabetes beyond the risk reduction possible through diet alone. Physical activity lowers LDL cholesterol and triglycerides, increases HDL cholesterol, reduces abdominal fat as measured by waist circumference, and may protect against a decrease in muscle mass during weight loss.

Health professionals deem physical activity important for persons who are overweight because it leads to increased expenditure of energy and may serve to inhibit food consumption by reducing appetite. Although it generates only very modest weight loss—a 2 to 3 percent decrease in body weight or body mass index (BMI)—physical activity is helpful for preventing regain of lost weight.

Like those who have been inactive or sedentary, overweight people are advised to initiate physical activity slowly and gradually. Walking and swimming at a slow pace are ideal activities because they are enjoyable, easy to schedule, and less likely to produce injuries than many competitive sports. Table 6.1 is an example of a walking program that progressively increases physical activity. Further, because amounts of activity and the resulting health benefits are functions of the duration, intensity, and frequency, the same amounts of activity may be obtained in longer sessions of moderately intense activity such as FIGURE 6.2
Percent of adults aged 18 years and over who engaged in regular leisure-time physical activity, 1997–2003 brisk walking than in shorter sessions of more strenuous activities such as running. Table 6.2 shows how a moderate amount of activity—physical activity that uses about 150 calories of energy per day for a total of about 1,000 calories per week—can be obtained in a variety of ways. Table 6.3 shows how performing common household chores, and even such self-care activities as using a wheelchair, may be used to fulfill requirements for moderate amounts of physical activity. Changing routines to include walking up stairs rather than taking an elevator or parking further than usual from work, school, or shopping are ways to increase physical activity incrementally. Even reducing sedentary time, such as hours spent in front of the television, video game system, or computer can serve to increase energy expenditure.

FIGURE 6.3
Percent of adults aged 18 years and over who engaged in regular leisure-time physical activity, by age group and sex, January–June 2003

Table 6.2 also shows the relationship between the intensity and duration of physical activities by comparing the amount of time a 154-pound adult must spend performing each activity to expend 150 calories. It is interesting to note that just five additional minutes of walking at a moderate pace expends the same number of calories as walking at a brisk pace.

A study conducted by John Jakicic and his colleagues at the University of Pittsburgh Physical Activity and Weight Management Center, "Effect of Exercise Duration and Intensity on Weight Loss in Overweight, Sedentary Women: A Randomized Trial" (Journal of the American Medical Association, vol. 290, no. 10, September 2003), confirmed the weight-loss benefits of even moderate exercise. The study divided 201 women aged twenty-one to FIGURE 6.4
Age-sex-adjusted percent of adults aged 18 years and over who engaged in regular leisure-time physical activity, by race/ethnicity, January–June 2003 forty-five into four groups. Two groups of women expended 1,000 calories per week walking at a moderate pace for forty minutes a day. The other two groups expended 2,000 calories per week; one group walked at a moderate pace for sixty minutes a day and the other at a vigorous pace for forty-five minutes a day. All of the study participants reduced their calorie consumption to between 1,200 and 1,500 calories per day. The investigators found no differences based on different exercise durations and intensities—one group of women lost almost as much weight—about 13 to 20 pounds over twelve months—from walking at a moderate pace as another group did from walking at a brisk pace.